Atrial activity during cardioplegia and postoperative arrhythmias.

Cardioplegia provides excellent protection for the left ventricle, but the right atrium may be poorly protected. Myocardial temperatures, right atrial electrical activity, and postoperative arrhythmias were assessed in 103 patients participating in two consecutive randomized trials comparing blood cardioplegia (n = 36), crystalloid cardioplegia (n = 38), and diltiazem crystalloid cardioplegia (n = 29). Both right atrial and right ventricular temperatures were significantly warmer (p less than 0.05) during delivery of the blood cardioplegic solution than during delivery of either the crystalloid or the diltiazem crystalloid cardioplegic solutions; the aortic root temperatures were 9 degrees +/- 2 degrees C with blood cardioplegia and 5 degrees + 1 degrees C with both crystalloid and diltiazem crystalloid cardioplegia. Atrial activity during cardioplegic arrest was greatest with blood cardioplegia (12 +/- 3 beats/min), lower with crystalloid cardioplegia (10 +/- 2 beats/min), and minimal with diltiazem crystalloid cardioplegia (5 +/- 1 beats/min, p less than 0.05). Perioperative ischemic injury (by creatine kinase MB isoenzyme analysis) was greatest with crystalloid cardioplegia (p less than 0.05). Postoperative supraventricular arrhythmias (both treated and untreated) were more frequent after crystalloid cardioplegia (crystalloid, 63%; blood, 40%; diltiazem, 47%; p less than 0.05). Patients in whom supraventricular arrhythmias developed had significantly more postoperative ischemic injury (by creatinine kinase MB isoenzyme analysis, p less than 0.05). Blood cardioplegia reduced supraventricular arrhythmias by reducing ischemic injury despite warmer intraoperative temperatures and more right atrial activity. Diltiazem crystalloid cardioplegia reduced postoperative arrhythmias by improving intraoperative myocardial protection and suppressing intraoperative and postoperative atrial activity. Crystalloid cardioplegia cooled but did not arrest the right atrium intraoperatively, resulted in the most perioperative ischemic injury, and yielded the highest incidence of postoperative supraventricular arrhythmias.